INTRODUCTION: The analysis of asbestos fibers in lung tissue is complex due to both the biological matrix and the analyte. Lung tissue preparation techniques for asbestos burden analysis require the removal of organic matter to make the inorganic mineral components visible. The method's validation is challenging due to the analyte's inherent variability. This study outlines a procedure for validating an asbestos fiber analysis method in lung tissue. METHODS: At the Electron Microscopy Laboratory of ARPA Lombardia, a method using a plasma asher for freeze-dried lung tissue digestion was developed. The analysis is carried out with a scanning electron microscope equipped with an energy-dispersive x-ray spectrometer. Problems associated with interferences, instrument calibration and resolution, analytical sensitivity, recovery were described in detail. The trueness and precision of the analytical method were evaluated using certified reference materials in accordance with ISO 33403:2024 standard. RESULTS AND CONCLUSION: The developed method underwent a rigorous validation process to ensure metrological traceability of the results. Using validated analytical methods with consistent counting rules ensures comparability of data across laboratories while guaranteeing traceable results.